The goal of this research is to develop tactual aids for the deaf and deaf-blind that may serve as substitutes for hearing in the communication of speech and environmental sounds. Proposed research aims to increase understanding of the basic sensory properties of the tactual system and to develop improved strategies for encoding and displaying speech and other sounds that may lead to improved tactual communication devices. Research will follow four lines: (1) research on the basic properties of the kinesthetic and cutaneous sensory systems of the hand, conducted with a view towards increasing information transfer through manual tactual displays by quantitatively measuring the static and dynamic information- transmission potential of the hand using a multi-finger device capable of delivering both kinesthetic and cutaneous stimulation. This work will include studies of the role of the kinesthetic sense in thickness discrimination and of the role of contact force in tactual stimulation; (2) research conducted to assess the performance of deaf adults who are using wearable tactual aids for extended periods of time in the field, to determine benefits to speechreading and profiles of the use of devices. Work includes studies of the effects of training on performance with tactual devices and the integration of tactual information with speechreading and auditory cues; (3) research conducted towards the development of improved tactual communication devices as aids to speechreading, which may be capable of providing substantial benefits to speechreading and which may be used effectively within modest periods of learning. Research will focus on improving the reception of voicing through tactual reception of acoustic or articulatory-based supplementary signals; and (4) research conducted to evaluate signal-processing schemes and displays for the reception of environmental sounds. Work will include the development of methods for measuring the reception of environmental sounds, evaluation of the reception of environmental sounds through various existing tactual display systems, and exploration of the display of these signals relative to displays developed for speech.